Low-cost, earth abundant materials, such as Cu2ZnSn(S,Se)4 (CZTS), have been developed as an alternative to higher cost, less available copper indium gallium selenide (CIGS) absorber materials for next generation thin film photovoltaic devices. CZTS is one of the most promising materials for fabricating low-cost thin film solar cells. CZTS consists of earth abundant materials like copper (Cu), zinc (Zn) and tin (Sn) and has band gap energy of from 1.4 electron volt (eV) to 1.5 eV and an absorption co-efficient of 104 cm−1. See, for example, Hideaki Araki et al, “Preparation of Cu2ZnSnS4 Thin Films by Sulfurizing Electroplated Precursors,” Solar Energy Materials & Solar Cells, 93, 996-999 (2009), P. M. P Salome et al., “Influence of Selenization Pressure on the Growth of Cu2ZnSnSe4 Films From Stacked Metallic Layers,” Phys. Status. Solidi C 7, no. 3-4, 913-916 (2010), Masato Kurihara et al., “Kesterite Absorber Layer Uniformity From Electrodeposited Pre-Cursors,” Phys. Status. Solidi C 6, no. 5, 1241-1244 (2009), Jonathan J. Scragg et al., “New Routes to Sustainable Photovoltaics: Evaluation of Cu2ZnSnS4 as an Alternative Absorber Material,” Phys. Status. Solidi (b) 245, no. 9, 1772-1778 (2008), A. Ennaoui et al., “Cu2ZnSnS4 Thin Film Solar Cells from Electroplated Precursors: Novel Low-Cost Perspective,” Thin Solid films 517, 2511-2514 (2009) and U.S. Patent Application No. 20090205714 filed by Kuhnlein et al., entitled “Metal Plating Composition and Method for the Deposition of Copper-Zinc-Tin Suitable for Manufacturing Thin Film Solar Cell.”
Vacuum deposition processes are typically used to form CZTS absorber layers in photovoltaic devices. Vacuum deposition is however costly. Further, with vacuum deposition it is difficult to deposit the material over large areas uniformly.
Therefore, improved techniques for forming CZTS absorber layers in photovoltaic device applications would be desirable.